WTW COD Pre-filled Reagent Kit C3/25 (Cat. No. 14541)

Overview

The WTW COD Pre-filled Reagent Kit C3/25 (Catalog No. 14541) is a rigorously validated, ready-to-use colorimetric reagent system engineered for precise Chemical Oxygen Demand (COD) determination in aqueous samples using photometric analyzers. Based on the dichromate oxidation principle under acidic, high-temperature digestion (typically 150 °C for 2 h), this kit quantifies the oxygen-equivalent demand of oxidizable organic and inorganic substances—enabling robust water quality assessment across regulatory and operational contexts. Designed exclusively for seamless integration with WTW’s photometric platforms—including the NOVA 30, NOVA 60, Prove, Move 100, photoFlex, photoLab S6/S12, and photoLab 6100/6600/7100/7600 series—the C3/25 kit eliminates manual reagent preparation, minimizing analyst error and cross-contamination risk while ensuring method traceability.

Key Features

• Pre-calibrated, pre-weighed reagents: Each vial contains a stabilized mixture of potassium dichromate, sulfuric acid, silver sulfate catalyst, and mercury sulfate (for chloride masking), sealed under inert atmosphere to guarantee shelf-life stability and inter-batch consistency.
• Integrated barcode identification: A proprietary black barcode label on each vial enables automatic method selection and parameter loading on compatible WTW photometers—reducing setup time and eliminating manual method entry errors.
• Traceable quality assurance: Supplied with batch-specific Certificate of Analysis (COA) and Certificate of Quality (COQ), documenting raw material sourcing, production controls, and performance verification against NIST-traceable COD standards.
• Flexible cuvette compatibility: Optimized for use with standard 16-mm square glass or quartz cuvettes; supports dynamic range adaptation via dilution or alternate vial selection without instrument recalibration.
• Regulatory alignment: Validated per U.S. EPA Method 410.4 and German DIN 38409-Part 41, supporting compliance reporting for wastewater discharge permits, drinking water surveillance, and industrial effluent monitoring under ISO/IEC 17025-accredited laboratories.

Sample Compatibility & Compliance

The C3/25 kit is validated for direct analysis of clarified, low-turbidity aqueous matrices including municipal wastewater, surface water, groundwater, drinking water, process water from food/beverage or pharmaceutical manufacturing, and treated industrial effluents (e.g., electroplating rinse waters, bioreactor supernatants). For samples containing >1000 mg/L chloride, optional chloride compensation protocols—using supplemental HgSO₄ or AgNO₃ pretreatment—are documented in the included technical bulletin. All reagents are manufactured in accordance with EU REACH Annex XIV restrictions and carry full SDS documentation compliant with GHS classification. The kit meets GLP audit requirements for data integrity, including full chain-of-custody documentation and retention of COA/COQ records for ≥5 years.

Software & Data Management

When used with WTW photoLab instruments running firmware v3.2+, the barcode triggers automatic assignment of wavelength (600 nm), measurement protocol (digestion + photometric read), and calibration curve (quadratic fit, R² ≥ 0.999). Raw absorbance values, digestion timestamps, operator IDs, and environmental metadata (ambient temperature, humidity) are logged with ISO/IEC 17025-compliant audit trails. Export formats include CSV, PDF analytical reports, and XML for LIMS integration. Optional FDA 21 CFR Part 11 compliance modules support electronic signatures, role-based access control, and immutable record archiving.

Applications

• Continuous monitoring of influent/effluent COD in municipal wastewater treatment plants (WWTPs)
• Process control in anaerobic digesters and activated sludge systems
• Quality release testing of potable water post-disinfection
• Effluent compliance verification for textile, tannery, and semiconductor manufacturing
• Environmental impact assessments for agricultural runoff and aquaculture discharge
• Research-grade COD profiling in biodegradability studies (e.g., OECD 301 series)

FAQ

What photometric instruments are fully compatible with the C3/25 kit?
The kit is validated for use with WTW NOVA 60, Prove, photoLab S6/S12, and photoLab 6100/6600/7100/7600 series. NOVA 30 and Move 100 require firmware update v2.8+ for full barcode recognition.
Can the C3/25 kit be used for samples with high chloride content?
Yes—chloride interference up to 2000 mg/L is suppressed by the built-in HgSO₄ masking agent. For chloride >2000 mg/L, refer to WTW Application Note AN-COD-07 for alternative digestion protocols.
How should opened reagent vials be stored?
Unopened kits retain stability for 24 months at 15–25 °C. After opening, store vials in original packaging at 4–8 °C and use within 30 days. Avoid repeated thermal cycling.
Is method validation documentation available for regulatory submissions?
Yes—each shipment includes a signed COA referencing NIST SRM 1096a/b COD standards, plus a full validation report covering specificity, linearity (10–150 mg/L, r² ≥ 0.9995), precision (≤3% RSD, n=6), and recovery (96–104%).
Does the kit support automated sample handling systems?
The C3/25 vials are dimensionally compatible with WTW AutoSampler AS-25 and third-party robotic liquid handlers equipped with 16-mm cuvette grippers and barcode scanners. Integration requires custom script configuration via WTW LabConnect SDK.